Process for making a hydrocarbon extending oil for rubber



United States Patent Delaware N0 Drawing. Filed Jan. 30, 1962, Ser. No. 169,960

2 Claims. (Cl. 208271) This invention relates to the production of an oil useful in the processing of rubber. More particularly, this invention relates to the production of a non-staining extend ing oil useful in the processing of rubber.

Petroleum extending oils are employed in the manufacture of rubber primarily to reduce its cost. The extending oil, however, also enhances certain properties in the final rubber product. For example, oil extended rubbers result in less heat build-up in automotive tires in service than do non-oil extended rubbers.

The petroleum extending oils so employed in rubber manufacture must have certain characteristics. First, the oils must be fully compatible with the rubber so that no oil .Will migrate to the surface of articles produced from I such a rubber. Secondly, the oils must have low volatility sothat oil is not lost from the rubber during its process ing. A third requirement for a special type of oil extended rubber is that the oil must not cause discoloration 'of light colored articles produced from the rubber nor cause migration staining of painted surfaces in contact with the rubber. This special type of rubber is termed non-staining, oil extended rubber. To obtain better compatibility it is generally desirable to have a stock in the lubricating oil range, i.e.,- an oil with a viscosity of more than 50 SSU at 100? F. The maximum viscosity of the oil is limited by case of dispensing it into the rubber composition, i.e., it must be sufliciently fluid to allow its addition to the mixing equipment. Aromatic oils are preferred for compatibility but in general such oils cause considerable discoloration and staining. Paraffinic oils have good stain qualities but poor compatibility. Thus,

it has been found that naphthenic oils represent the best compromise between compatibility and staining characteristics. Petroleum oils having a high content of naphthenes, however, may still not be suitable for extending non-staining rubber due to the presence of trace amounts of compounds causing stain and discoloration.

In accordance with this invention, a process has been devised whereby oils of substantial naphthenic constituency containing the compounds causing stain and discoloration can be treated to provide nomstaining extending oils useful in the processing of rubber. Thus, according to this invention, a petroleum hydrocarbon oil useful in theprocessing of rubber is prepared by a process in- ,cluding the step of subjecting a lubricating oil ralfinate are separated and the separated raffinate is treated with Such processes are well-known.

3,193,497 Patented July 6, 196,5

concentrated sulfuric acid in an amount of about 5 to 30 pounds per barrel of oil.

Suitable rubber polymers in the processingl'of which the extending oils of my invention are employed include natural ruber, synthetic natural rubber prepared by polymerizing isoprene, butadiene-styrene polymers (GR-S), and chloroprene polymers (neoprene) and oil masterbatched GR-S polymers.

The lubricating oil raffinates useful as starting materials in the process of'this invention include the lubricating oil raflinates having a pour point below about 25 F. obtained by the solvent extraction of a lubricating oil stock derived from a crude oil of substantial naphthenic constituency with a solvent selective for aromatics. The lubricating oil raflinates preferably have a maximum A.P.I. gravity of about 30 and a viscosity range of about 35 to 180 SSU at 210 F. and a minimum viscosity of about 50 SSU at F.

If the lubricating oil raflinate has a pour point, above about 25 F., then it should be subjected to a solvent dewaxing step. The solvent dewaxing step is carried out by contacting the raflinate with a solvent elfective to remove waxy components and in an amount sufiicient to reduce the pour point to about 0 to 25 F. The manner of contacting is conventional, i.e. is carried out by admixing oil and solvent and passing the mixture through a chiller and then to a filter to remove wax and distilling the solvent from the dewaxed oil. The solvents effective for this purpose are well-known and include, for example, methyl ethyl ketone admixed with benzene and/ or toluene, propane, and a mixture of ethylene dichloride and benzene. Generally, about 100 to 600 percent of solvent based on the oil is sufiicient but this can vary with the characteristics of the raflinate. tures of about 0 to 20 F. are used.

The lubricating oil stocks useful in the preparation of the lubricating oil rafiinates areobtained from crude oils of substantial naphthenic constituency as distinguished from paraffinic oils, e.g., Pennsylvania base oils. Particularly advantageous oils are Mid-Continent (mixed) and naphthenic crudes. Both distillate and residual lubricating oil stocks can beemployedl Solvents which can be used in the production of the lubricating oil rafiinates include particularly phenol but other solvents selective for aromatics suchas nitr'obenzene, furfural, and liquid sulfur dioxide arealso useful. For example, phenol extraction comprises passing a feed stock through a phenol treating tower, removing a raflinate oil from the top of the tower, removing an extract oil from the bottom and removing the phenol from the 'raflinate oil and extract oil by distillation.

The acetone extraction step of this invention can be carried out in either a batch or continuous system of the type normally employed for solvent extraction of lubricating oil distillates and such as employed in preparing the lubricating oilraffinate feed material. The amount of acetone employed can vary from 50 to 700 volume percent of feed material, preferably 100 to '400 volume percent of feed material. The acetone extraction temperature can vary from 40 to F. and the pressure from atmospheric to 50 p.s.i.g. The amount of acetone Generally, filter tempera- '9 and the temperatures and pressures employed are dependent upon the properties of the specific feed material and the properties of the acetone rafiinate which upon further treatment will yield a rubber extendingoil having a the desired characteristics.

The sulfuric acid treating step of the process of this invention comprises contacting the rafiinate from 'the ace tone extraction" with concentrated sulfuric acid, separat ing sludge from the resulting acid oil, neutralizing the acid oil with a solution efiective to neutralize the acid oil and then washing the neutralized oil with water to remove excess neutrali'zer. The concentrated sulfuric acid .should be at least 95% acid and preferably 98% acid; The temperature of acid treating can rangefrom about 80 to 150-F. and preferably about 80 to 100 F.

The amount of concentrated sulfuric acid can range from about 5 to 30 po1 1nds of acid per barrel of acetone'ralfinate again depending upon the properties of-the specific acetone rafiinate'employed and the desired characteristics of the rubber extending oil product.

'Thesludge' is removed from the acid oil by a pepper blow can be used to remove fine sludge. Solutions of sodium hydroxide or sodium carbonate are pre- 'ferred for the neutralization step' although'other neutralizing agents can be used. The'strength and amount of settling and 'ment, e.g. fuller earth, bauxite, and various activated clays.

'Alternatively the neutralized and Washed oil can be subjected to a mild hydrofinishing treatment employing a hydrogenation catalyst. Various methods for manufacturing such catalystshave been described in the art,

' May 24, 1960.

neutralizing solution is not critical provided that at least 120-percent of thetheoretical amount required, based on theacid number of the acid oil, is used.

platinum and palladium on alumina.

such as in Byrns Patent 2,325,033, and such catalysts generally consist of from about 2 to 5v percent by weight of cobalt oxide and 5 to 15 percent by weight of molybdic oxide, the balance being alumina. Also useful are, for

instance, nickel on porcelain, silica or alumina; molybdenum', tungsten, cobalt, nickel oxides and sulfides; and,

A preferred catalyst 'is cobalt 'rnolybdate supported on alumina. Such preferred catalysts can be prepared bythe method of Keith et al. described in US. Patent 2,938,002, dated Further, in the hydrogenation step a temperature of from 550 'to.750 F., a pressure of from 400 to 1500 p'.s.i.g. and a weight hourly space velocity. (Weight units of oil per Weight unit of catalyst per hour) of from 0.1 to 5.0 are used. The oil is, hydrogenated while it is in admixture with from 700to 5000 standard cubic feet of hydrogen'per barrel of oil. a a

The process of this invention will be furtherflillustrated by reference to the following examples.

EXAMPLE 1 phenol extraction of a Mid-Continent 2001SSU/210F.

y The neutralized oil is water washed until both oil and wash are neutral tophenolphthalein or a similar indicator. Anyof the common washingprocedures such as spray washing or air blowing a water wash can be employed- I have found, howeventhat it is important'that the water washing step of particularly 'heavystocks be carried out by spray washing to reduce thetendency for formation of troublesome emulsions during the washing step. Air blowing a Water wash or steam breaking results in troublesome emulsions. The use of spray washing, however, eflectively reduces the tendency for emulsion formation. 1 The neutralized and washed, oil can be subjected to further finishing steps although these are not essential. For example, the neutralized and washed oil canbe contacted raw lubricating oil stock to a viscosity index level of about 73 was extracted with an equal volume of acetone,

' treated with 30 pounds per barrelof 98% sulfuric acid,

neutralized with caustic, and contacted'with clay. The

- details of each treating step are set-forth below in TableI.

The finished processing oils were then subjected to a stain 'test' which consists of mixing equal quantities by weight of titanium di'oxide and the oil being. tested. Theresultant paste is exposed to ultra-violet light for 48 hours at about. 115 F. The surface of the paste is then examined for discoloration; The results from this type of test have been foundto correlate well with similar testing of actual rubber compositions. The'stain test results, shown in Table II, show that the process of thisinvention produce non-staining rubber extender oils. Also shown in Table 'II are the characteristics of the raflinat'e charge stock and withan adsorbent earth such as an adsorbent clay. The

treatment removes any sodium sulfonate soaps remaining in the oil from the acid treating step along with residual acids, solvents or other impurities and improves odorand color stability. It is important to remove soaps from the treated oilsince if oil containing soapsbecomes contaminated with water, e.g. during shipment or storage, a

moisture haze or partial emulsification would occur and the oil would be useless as a rubber processing oil. Pref; V erably, the treatment is carried out at a temperature of about 200 to 400 F.- Generally, a dosageof about 5 to 20 pounds of earth per barrel of treated oil issufiicient butthis amount can vary with the nature of the .oil and the processing conditions of the acid-treating and dewaxing steps. The treatment can be carried out by 0 direct contact of the oil with the earth in the well-known manner of contact filtration'wherein finely divided clay 'isadmxied with the oil to form a slurry which is heated .for a period of time'and the oil then separated. Alterriatively, the well-known percolation filtration method can be used wherein the earth is packedin atower and vso oil is charged to the top' and percolates through the bed ofearth and the filtered 'oil is removed from the'bottom' of the tower; By the term adsorbent earth, I mean to include the earths. conventionally used in such treatof the finished processing oil.

, Table I v CONDITIONS AND YIELDS 0N ACETONE EXTRACTION AND ACID TREATING :Acetone extraction conditions:

Acetone dosage, vol. percent 100.0

7 Air blow free S0 hrs. 1

' Settle, hours .l l Neutralize (20%. caustic sol.), percent water wash neutral 1 Clay contacting: i

' Attapulgus. clay, #/bbl. .........7 15 Temperature, F Q 180 A dewaxed lubricating oil raflinate obtained from the Table II ACID TREATED ACETONE EXTRACTED OIL TESTS ON CHARGE AND PRODUCTS Acetone Acetone Ev I Charge raifinate V I oil 1 acid treated Raflinate Extract Gravity, API 27. 1 27. 8 21. 2 29. Fla F 430 430 430 430 Fire, F 490 490 490 490 Viscosity, cs./100 F. 58. 52 56. 55 97. 26 52. 87 Viscosity, cs.l210 F- 6. 879 6. 810 8. 095 6. 688 Viscosity index--." 73. 7 76. 8 30. 8 83. our, 0 +5 10 +5 Color, ASTM- 2. 5 2. 5 5. 5 0. 5 Aniline poin 93.4 95.3 69.0 99.0 Refractive index, 71 1. 4925 1. 4898 1. 5183 1. 4059 Molecular weight 419 427 385 445 Density at C 0. 8886 0. 8850 0. 9235 0. 8783 Hydrocarbon analysis:

Viscosity gravity constant 0. 838 0. 832 0. 873 0. 824 Refractivity intercept 1. 0483 1. 0473 1. 0566 1. 0468 Percent aromatic carbon 12 10 25. 7. 0 Percent naphthenic carbo 29. 8 29 23. 0 29. 5 Percent parafiiu chain carbons 58 2 61 51 2 63. 5 T10; stain test Poor Trace (taint) EXAMPLE 2 Table III-Cont1nued A further sample of the dewaxed lubricating oil raf- Acid treating conditions Treat number finate of Example 1 was extracted with an equal volume of acetone to yield 91.4 volume percent of a raffinate oil. Samples of this raflinate oil were treated with varying L56 Sulfuric acid lbs./b 30 20 10 amounts of sulfuric acid and tested for stalning tendency. Acid Strengt ,pemen 98 98 98 The results show that stain properties gradually 1mprove Temperature, F- 85 85 85 with increased acid dosage. Details of treating and tests g{.Ej g; ;fffig g $8 on the oils are summarized in Tables III and IV below. 9 Y -D Be All blow free s0 hrs 1 1 1 Although not shown 1n Table III, 1f the acetone extraction sett1 ,1m 16 16 16 step is omitted, the acid treated oils have poorer stain fl fff f* ff characteristics, i.e. a 30 pounds per barrel 98% sulfuric ilg gfig 1b lbbl 15 15 15 acid treat on the lubricating oil raflinate charge oil yields Temperature, F ':::III: 180 180 180 on oil having medium stain. 4O

. Table IV ACID TREATED AOETONE EXTRACTED OIL TESTS ON CHARGE AND PRODUCTS Acetone Acetone raflinate acid treats Charge Tests oil Raffinate Extract 30 lb./bbl., 20 lb./bbl., 10 1b./bbl., 98% H3804 98% E30 98% H2504 Gravity. API 27. 1 27. 9 20.8 29.0 28. 6 28.0 Flash, F 430 430 430 440 430 440 490 490 490 495 490 495 58. 52 55. 66 102. 3 53. 17 54. 41 54. 81 6. 879 6. 892 8. 238 6. 696 6. 719 6. 739 73.7 80.4 27.0 83.1 79.7. 79.3 0 +5 -15 +10 +5 +10 2. 5 2. 5 6. 0 L1. 0 L1. 0 L1. 0 93. 4 95. 4 66. 5 98. s 97. 8 96. 6 1.4925 1.4901 1. 5208 1.4860 1.4873 1. 4884 419 440 385 463 448 444 0. 8886 0. 8846 0. 9235 0. 8786 0. 8812 0. 8823 Hydrocarbon analysis:

Viscosity gravity constant. 0. 8380 0. 8320 0. 8770 0. 8240 0. 8270 0. 8310 Refractive intercept 1. 0483 1. 0477 1. 0591 1. 0467 1. 0467 1. 0473 Percent aromatic carbons- 12. 0 10 27. 5 7 7 5 Percent naphthem'c carbons 29. 8 30 20 5 30 30 29. 5 Percent paratfin chain carbons 58.2 52.0 63 63 61. T1 2 Poor Medium+ Trace Light Med ll I claim:

Table III CONDITIONS AND YIELDS ON ACETONE EXTRACTION AND ACID TREATING Acetone extraction conditions Acetone dosage, vol. percent 100 Temperature, F 73 Mixing time, min" 5 Settling time, min 30 Yield of solvent tree oil, vol. percent; 91. 4

1. The process of preparing a hydrocarbon oil useful in the processing of rubber including the steps of subject- 0 for aromatics, to a treatment with acetone in an amount of about 50 to 700 volume percent of the lubricating oil feedstock at a temperature within the range of about 40 to 150 F. and a pressure within the range of about 0 to 50 p.s.i.g., separating a raffinate and an extract, and

V treating the separated raffinate with concentrated sulfuric 7 7 acid in an amount. of about 5 to 30 pounds per barrel of oil.

2. The process of claim 1 wherein the acid-traitdrafl 5 finate is further treated with an adsorbent earth, V References Cited by the Examiner 1 UNITED STATES PATENTS 8 V Forrest 208-45 Kalinowski 20845 Rausch -20845 F 0x1; 20.87271 Garwin -L 208-4S V PHONSOQDVJSULLIVAN, Primary Examiner. 1,698,471 1/29 Brarxsky et a1; ..2(}8 -45 h. .i 

1. THE PROCESS OF PREPARING A HYDROCARBON OIL USEFUL IN THE PROCESSING OF RUBBER INCLUDING THE STEPS OF SUBJECTING A LUBRICATING OIL RAFFINATE HAVING A POUR POINT BELOW ABOUT 25*F., OBTAINED BY THE SOLVENT EXTRACTION OF A LUBRICATING OIL STOCK DERIVED FROM A CRUDE OIL OF SUBSTANTIAL NAPHTHENIC CONSTITUENCY WITH A SOLVENT SELECTIVE FOR AROMATICS, TO A TREATMENT WITH ACETONE IN AN AMOUNT OF ABOUT 5 TO 700 VOLUME PERCENT OF THE LUBRICATING OIL FEEDSTOCK AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 40* TO 150*F. AND A PRESSURE WITHIN THE RANGE OF ABOUT 0 TO 50 P.S.I.G., SEPARATING A RAFFINATE AND AN EXTRACT, AND TREATING THE SEPARATED RAFFINATE WITH CONCENTRATED SULFURIC ACID IN AN AMOUNT OF ABOUT 5 TO 30 POUNDS PER BARREL OF OIL. 